Mechanism for preparing molds for dental castings



E. l. ROSHEHVI.

MECHANISM FOR PREPARING MOLDS FOR DENTAL CASTINGS.

APPLICATION FILED APRJI, I921.

Patented Maylfi, 1922.

BILLING I, ROSHEIM,

FEW i sis.

OF ROLAND, IOWA.

MECHANISM' FOR PREPARING lVIOLDS FOR, DENTAL CASTINGS.

To all 107mm may concern Be it known that I, ELLiNs I. Rosrmmr, a citizen of the United States, and a resident of Roland, in the county of Story and State of Iowa, have invented a certain new and useful Mechanism for Preparing Molds for Dental Castings. of which the following is a specification.

The object of myinvention is to provide a mechanism for use in preparing molds for dental castings.

More particularly, my object is to provlde a mechanism preferably including a support with a rotary member mounted thereon adapted to hold a form with a mold therein in suitable position to be heated. the structure being such that the mold may be readily accessible to the heat and being mounted for rotation. so that the heat may be uniformly applied.

A further object is to provide such a machine adapted to hold the mold in such a way, so that the mold may be readily visible to the operator for permitting the most careful watching of the mold for determin ing the progress of the heating operation.

Still a further object is to provide in connection with such a machine. a movable heater member with suitable controlling ele ments therefor.

lVith these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my device. whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawings, in which Figure 1 shows a perspective View of a machine embodying my invention.

Figure 2 shows a perspective View of the mold holding element with the form and mold received therein.

Figure 3 shows a detail, sectional view taken on the line 33 of Figure 1.

Figure 4 shows a detail, sectional view taken on the line l4t of Figure 3; and

Figure 5 shows a detail, sectional view through the fuel control valve, taken on the line 55 of Figure 1. I

My improved machine. herein under consideration is designed to be used in connection with other mechanical devices, such for instance as my improved sprue former, disclosed in my Patent, No. 1,387,558, issued Specification of Letters Patent.

Patented May 16, 1922. 1921. Serial No. 460,402.

August 16, 19:21, and to be used in connection with my complete improved process for making dental castings quickly.

In carryingout my process, it has been my purpose to shorten the time required for performing the various steps of the process and to provide mechanisms and material for making molds for dental castings and makmg the castings, whereby it would be possible to make a complete casting after a local anesthesia has been used, and before the tissues regain their ordinary sensitiveness.

Heretofore, so fa r as I am aware, no process has been practiced in a successful practical way whereby a complete casting could be made and placed in the tooth in the time just mentioned.

It is obvious that it is highly desirable to be ahle to complete the casting and put it into the tooth during the period, mentioned and for the successful accomplishing of such purpose, it is necessary that all the steps be definite and that the results must be accurate and uniform in all cases.

In making a dental casting, it is necessary to first prepare the cavity and then to fill the cavity with wax and make a wax pattern. This wax pattern is then removed from the tooth and pin is inserted into the pattern. The pattern is then washed and painted and the pin is placed in a sprue former, which supports a detachable mold ring or form.

It will be obvious that the wax pattern will then be received within such ring and the molding material may then be poured into the ring.

To set the mold and either boil out or absorb the wax and then harden the mold has been heretofore a process requiring a relatively long time. It is my purpose to provide a process and mechanism, whereby the mold can be made and set and the wax absorbed Or boiled out and the mold hardened in a very short time.

For accomplishing this purpose. I have invented an investment compound. which is not a subject of the present application.

Where my improved investment compound is used, it is poured into the ring above the sprue former, and the next step in the operation involves the use of my improved machine, which is the subject of the present application.

My improved machine comprises a base indicated in the accompanying drawings by the reference character 10. The base 10 has an upright member 11. Supported on the upper portion of the upright 11 is a suitable casing or the like 12, within which is the mechanism, which will now be described.

Supported in the casing 12 is a shaft 13. A spring motor device, such for instance, as the convolute spring 14 is connected with the shaft 13 and with a gear 15 loosely mounted thereon. A key 16 is provided for winding the spring 14.

Suitably mounted in the casing 12 is a second shaft 17. On the shaft 17 is a small gear 18, which meshes with the gear 15.

It will be understood that the shaft 13 projects through the wall of the casing 12 and that the key 16 is on the outside of such casing.

Mounted in the casing 12 and projecting therefrom is a shaft 19. On the shaft 17 is a gear 20 in mesh with the gear 21 on the shaft 19. On the outer end of the shaft 19 outside the casing 12 is a hub 22, which may be screwed onto the shaft 19 and held in position by a set screw 23, if desired.

Connected with the hub 22 is a disc or the like 24 from which there project laterally the form or mold engaging members. The mold engaging members, two in number, each consist of a pair of parallel spring wires 25, spaced from each other and connected at their outer ends by outwardly curved cross members 26. 27Mounted in the casing 12 isanother shaft On the shaft 19 is a gear 28, which meshes with the gear 29 on the shaft 27.

In the casing 12 is still another shaft 30. A gear 31 on the shaft 27 meshes with the gear 32 on the shaft 30.

On the shaft 30 is a resistance element such for instance as a fan or the like 33.

For frictionally locking the shaft 30 against rotation when the device is not in operation, I have provided a brake device, consisting of the brake member 34, which is plvoted at 35, substantially above the shaft 30, and has one end adapted to engage the shaft 30 when the brake member 84 is in one position of its movement.

Connected with the brake member 34 is an upwardly extending arm36 on the upper end of which is a weight 37 The parts are so arranged, as illustrated in Figure 3, that when the brake member 34 engages the shaft 30, the arm. 86 will be inclined from vertical. in such a way that gravity tends to pull the weight 37 down wardly for thereby pressing the brake member 34 against theshaft 30 and thus holding the brake member 84 in frictional engagement with such shaft.

When it is desired to release the brake, the

weight 37 is swung past center for swinging the brake member 34 away from the shaft 30, and it will be obvious that after the arm 36 has passed the vertical center, the weight 37 will tend to hold the brake member 34 away from the shaft 30.

1 provide for use in connection with my improved device, a burner element 88, which may be of any suitable type adapted to accomplish the purpose.

On the base 10 is a fuel conducting pipe 39, which is preferably connected with the burner 38 by means of a flexible fuel con.- ductor, such for instance as the rubber tube 40, shown in dotted lines in Figure 1.

For controlling the passage of fuel through the pipe 39, there is provided a valve 41, having a stem 42 extending upwardly slightly from the base 10 and having a head 43 adapted to be readily manipulated by the fingers for controlling the valve 41.

On the stem 42 is an indicating finger 44, which travels over a graduated dial 45.

It will be obvious that after the parts have been once adjusted, and assuming that the fuel supply is reasonably constant in pres sure, the heat supplied by the burner may be easily controlled and readily determined by varying the position of the valve 41 and observing the position of the finger 44. lVith some burners, the degree of heat can be readily checked or ascertained by the colors the flame.

Assuming that a wax pattern has been made and has been supportedon the sprue former by means of a pin projected into the pattern and resting in the hole in the sprue former provided therefor, and that the ring or form 46 has been placed on the sprue former, and that the investment material has been placed in the ring 46, then where my process is employed and especially where my investment material is used, the mold. is allowed to set for a few seconds, and thereafter it is highly desirable that a limited amount of heat be uniformly applied to the mold for a few seconds. For thus applying the heat, my'present machine is used.

The ring 46 with the mold 47 therein is slipped between the mold or form receiving members as shown in Figure 2.

Assuming that the burner is ready for use, it may be slipped to position directly under the ring 46. Assuming also that the spring 14 has been wound up, it will be seen that by moving the brake device to releasing or inoperative position, the spring will be made operative and rotation will be imparted to the ring 46. Thus the heat will be uniformly applied to the mold 47 from all sides. By knowing the degree of heat and by experiments, it is easy to determine how long the heat should be applied, in order that the mold may be uniformly heated without heating the central portion thereof where the wax form is located to a degree hotter than 110 Fahrenheit. 9

After the mold has been uniformly heated for a few seconds, as above set forth, the op erator can slide the burner 38 away from below the mold. The brake is applied for stopping the rotation of the mold and the mold isthen allowed to set for a couple of minutes.

After this setting period has expired, the brake is again released and the rotation of the mold will again be started. The burner may then be slid again to position below the mold and the second heating operation performed.

During the second heating operation, the wax form disappears either by being absorbed in the surrounding body of invest ment material or by being partiallv boiled out through the hole 48 left by the pin.

After the second heating has been completed, the mold may be allowed to stand for a minute or two depending upon the size of the pattern and the casting to be made, and also upon the degree of heat which was applied during the second heating operation, and also depending upon the length of time of the second heating.

The mold may then be removed from the holder members and is ready for the casting operation.

On the upper part of my device is a suitable bracket 49 to support a stop watch or the like for use in carrying out my process.

It will be seen that with a machine of this kind, many advantages are obtained.

It is highly desirable that the heat applied to the mold 47 should be applied uniformly to all sides thereof.

It is also highly desirable that the mold and especially the end thereof which was formed on the sprue former, should be clearly visible to the operator during the heating process. This is true because the drying out of the mold is indicated by a change of the color thereof, which is readily observable, and this is especially true where my special investment material is used.

It will be obvious that the desirable objects are readily and fully secured by my improved machine here shown.

The wire engaging members which hold the ring 46 are such that they do not interfere with the heating of the mold, and it is obvious that it is easy to heat the mold uniformly.

The arrangement of the holding devices is such that the sprue former end of the mold which is smooth may be readily and easily observed for watching the changes therein and especially in the color thereof during the heating operation. The change of color is much more observable at the sprue former end of the mold than at the other end. The

sprue former end must be down or at least the mold must be arranged on a horizontal aXis to permit the wax to be partially boiled out through the opening left by the pin.

It thus is clear that the sprue former end of the mold must be inclined downwardly or horizontally in order to permit the partial boiling out of the wax, and it is also obvious that it would be undesirable to irrange the form with the sprue former end down, be cause of the diiiiculty in observing it.

It therefore follows that in practice the horizontal arrangement provided for in my machine is the most desirable and has the most advantages.

Another advantage of. the horizontal. arrangement is thatit is easier to then rotate the form in the heat of a flame for heating the form uniformly to the best advantage.

I have found that by heating the mold in l'iori'zontal position from below and rotating the mold, I secure a more uniform heat throughout the mold than in other ways, such for instance as shooting jets horizontally against the form.

Another advantage in arranging the mold horizontally during the heating process may be explained.

I find in making a mold that it is desirable to absorb much of the wax pattern as pos sible into the mold material. I find, however, that when the mold material becomes saturated. with the wax, it is then desirable to permit the remaining wax to boil or flow out of the mold.

It is obvious that where a small pattern is employed, the problem involved is somewhat different than that involved where a larger pattern is used. By arranging the mold horizontally during the heating process, I find that where a small pat-tern has been made, the wax is properly absorbed, and the proper wax lining is formed.

On the other hand, if the pattern is larger, I find that the wax is absorbed to the proper amount and the lining is formed and the remaining wax is easily boiled out.

By arranging the mold in the way shown herein, proper disposition of the wax is automatically always had, and this is accomplished without much care as to the degree of heat applied or the care in the gradual increasing of the heat.

I find with very few experiments that the heat can be stopped when the proper degree has been reached by observing the colors at the end of the mold, as hereinbefore fully explained.

It should also be noted that after a few experiments the operator can determine by the time employed approximately when the heating should be stopped.

Another important advantage in using the mounting, whereby the mold may be rotated arises from. the fact that after the heating has been completed and the heat has been withdrawn, the rotation of the mold may be completed. This is important in order to secure a uniform inward progress of the heat from all sides to the mold.

It is well-known that heat tends to rise, and it will be seen that if the mold were heated and. then stopped in its movement, the heat would. not travel uniformly from all directions toward the pattern at the center of the mold from the periphery of the mold. By continuing the rotation. of the mold, after the heat is withdrawn, the heat will, approach the pattern with. a uniform movement from all sides and accomplish the partial carbonizing of the wax.

Some changes may be made in the arrangement and construction of the parts of my improved mechanism without departing from the essential features and purposes of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents, which may be reasonably included within their scope.

I claim as my invention:

1. In a device of the class described, a base, a burner, adjustably movable thereon, means on said base for regulating said burner and indicating such regulation, an upright member, a form holder thereon comprising resilient engaging elements adapted to hold a dental. mold form for exposing said form freely to the heat of said burner with the sprue former end of said form plainly visible, means for imparting rotary motion on a horizontal axis to said holding means, and means for regulating such motion.

2. In a device of the class described, a base, a burner movable thereon, an upright "heat of said burner, with the sprue former end of said mold form plainly visible, and

means for imparting rotation on a horizontal axis to said holder.

In a device of the class described, a base, a burner movable thereon, an upright member, a dental mold form holder having resilient engaging members for supporting a mold form for freely exposing it to the heat of said burner, with the sprue former end of said mold form plainly visible,means for imparting rotation on a horizontal axis to said holder, and means for regulating said rotation.

4. In a device of the class described, a base, a burner movable thereon, an upright member, a horizontal shaft on said upright, a form holder on said shaft, comprising spaced resilient engaging members between which a form may be inserted from in front, with its sprue former end plainly visible, means for imparting rotary motion to said shaft for rotating a form held in said holder and exposed to the heat of said burner, and

a brake device for controlling said last means.

5. In a device of the class described, a base, a supporting element thereon, a dental mold form holder, mounted thereon for rotation 011 a horizontal axis, a burner, and 

